All right, then: Get ready for some great coffee-table books devoted to your holiday apes, your songbirds, your ocean, your batfish and your cirrhotic livers -- and if you think the latter doesn't fit the theme of nature and the environment, welcome to the "ghastly and sacral" operating theater of THE SACRED HEART: An Atlas of the Body as Seen Through Invasive Surgery by Max Aguilera-Hellweg (Bullfinch; 128 pages; $50).

Definitely not for everyone, and certainly not for the fainthearted, this bold and original volume of photos ranging from lung resection and hysterectomy to hip replacement and brain surgery typifies the diversity of gift books this season, even within a narrow category.

Lit with pinpoint spots and set against a background as black as night, the book's startling photos bring us so deeply inside the gristle and rack of human tissue that we are changed utterly -- in awe of nature's original creation as well as the surgeon's invasive instruments.

Amid a chest cavern or womb, a knee joint or eye socket, the operating team's delicate and tightly gloved hands lean, push, pull back and haul out giant masses of bloody matter as tenderly and precisely as they cut, probe, filet, transplant and sew.

It takes some getting used to: Here is a complete eyeball pulled out for investigation during a cornea transplant; a liver tumor plucked as gently as a freshly laid egg from a bed of blood-ripened tissue; the base of a penis sliced Open and parted to make way for the "Rolls Royce" of penile pumps; a man's face completely covered by his peeled-back scalp.

But with Aguilera-Hellweg's explicit and surprisingly personal text ("Many times while working on this project, I thought that perhaps I was mentally ill"), images that appear ghoulish at first soon become a legitimate art form. "The Sacred Heart" is an unforgettable, groundbreaking book.

Nature's same "elegant body plan" -- this time among the fliers and the singers -- is beautifully displayed in SONGBIRDS: Celebrating Nature's Voices by Ronald Orenstein (Sierra Club; 224 pages; $35), a glorious celebration of avian musicality and form: Songbirds make up half the bird population in the world, says scholar and birder Orenstein, and they're as resourceful and talented as any human.

He notes that crows have been seen using tools and, even, making implements to forage for ants, while male bowerbirds paint the walls of their elaborate nests with the juice of crushed berries as a means to lure females. Songbirds of northern regions, like the black-capped chickadee, are able to lower their body temperature by 45 to 55 degrees, and don't get too close to the hooded pitohui of New Guinea -- its striking black-and- orange feathers are poisonous.

The photos reveal rarely seen songbirds with the most magnificent plumage -- the fluffed-up red and blue feathers and curlicue tails of the bird of paradise, the dual pink pancakes of the wattled ploughbill; the ornate fan of red and black that spurts like a fountain from the top of the orangish royal flycatcher's head.

The text answers every question you never thought to ask. Why do songbirds sing? Orenstein says males want to attract females, repel rivals, sound alarms and offer challenges. More than 200 species of birds sing duets, and there is no such thing as "the" song of a songbird -- the musical calls are too complicated and varied to be labeled anything but a "song repertoire."

Orenstein points out that songbirds themselves have told us "what names to call them: currawong, eechong, uguisu, chiffchaff, phoebe, pewee" and hundreds more. His chapter on "Family Values" will astonish structural architects as well as anthropologists -- but then, so will the chapter of the same title in MOTHER NATURE: Animal Parents and Their Young by Candace Savage (Sierra Club; 118 pages; $27.50).

Here we learn, predictably perhaps, that warm-blooded creatures "are universally and irrevocably committed to parenthood," so the pictures of adorable babies mewling and wobbling and suckling are sometimes heart-stopping (don't miss the white-tailed fawn with eyelashes as long as your finger).

But thanks to Savage's authority and humor, we learn how animals handle species-crossing issues that aren't so familiar -- why some females (lions, for example) nurse each other's young while others (black-tailed prairie dogs) kill pups that aren't theirs; why some mothers (elephants) lead their extended families for decades while others (harp seals) wean and abandon their newborn in two weeks.

She shows us, too, why reproduction can be such "tough work" for coyotes, who bear up to 19 pups each spring and are pregnant again before the offspring are half grown, or cottontails, who "may have three litters in a year, for a total annual production of two dozen bunnies. It doesn't bear contemplating," concludes Savage, a mother herself.

In chapters that are both painful and humorous, Savage explains some of nature's omissions ("What about Dad?") as well as hard realities for any mom ("Honey, I Ate the Kids"). Her text is as much fun as the intimate shots (by photographers throughout the world) of the cutest baby weasels, Japanese monkeys, elks, cheetahs, zebras, red foxes and many others you ever did see.

Haunting and mercurial, the underwater photographs by Wayne Levin in THROUGH A LIQUID MIRROR (Editions Limited, P.O. Box 10150, Honolulu, Hawaii 96816, (808) 735-7644; 102 pages; $25 paper) surprise us with their black-and-white density. Most photographs of sharks, manta rays, green sea turtles and peacock flounder off the Hawaiian islands and Bikini Atoll dazzle us with the pink and blue of coral and sea, the colorful flash of a whipping tail.

But Levin takes us into the froth and murk and deep as we might see it through half-closed eyelids, or through dreams and imagination. Following a manta ray across the planetary floor of the ocean or a scalloped hammerhead in the midst of solid gray water, we could be in outer space; facing a school of gray reef sharks, their skins dappled by the sunlight beading through the ocean surface, we could be flying into enemy aircraft high above the island.

Berkeley writer Tom Farber notes in the often a bit too artistic introduction that water filters out many colors, and black-and- white film allows the photographer to use available (not artificial) light. But black and white also invites "ambiguity or, even, metaphoric possibilities" as the artist intends "not exactly to reveal the world beneath the surface but, rather, to deepen the mystery . . ."

This Levin does superbly, following surfers below the waves, humpback whales turning and diving, jellyfish seeming to explode with light, tourists standing knee-deep in fearlessly circling fish and a lone diver floating above the giant, silent forms of the sunken warships and bombers of World War II.

More traditional is the "photographic celebration" of SECRETS OF THE OCEAN REALM by Michele and Howard Hall (Carroll & Graf/Beyond Words; 162 pages; $39.95). Here the rainbow-colored shards of daylight penetrating the aquamarine world of an Australian sea lion or reflecting the curved haunch of a bottlenose dolphin contrasts beautifully with the (artificially) flash-lit sea dragon that seems to be growing leaves or the spotted iridescence of a Caribbean reef squid.

What gives these picture-postcard images character and depth, however, is the narrative of the Halls, a filmmaking couple whose companion video has been seen on PBS and whose underwater adventures are as human as their subjects are nonhuman. Michele Hall tells the story of stalking a skittish loggerhead turtle as silently as her rebreather (no bubbles) would allow, hiding behind coral outgrowths but at one point moving in "a little too quickly."

"The loggerhead looked up and noticed me. But instead of bolting away, the turtle turned and began swimming in my direction. He swam right up to me, paused to look at my underwater camera, and then tried to eat the light meter mounted above the lens! Apparently my light meter looked enough like a conch shell to interest the turtle." The two end up swimming side by side, with Hall actually gesturing to possible food prospects with her light meter and the turtle zipping off to feed on them.

How a certain (human) population once adjusted to its environment is the subject of DREAMLAND: America at the Dawn of the Twentieth Century (New Press; 207 pages; $40). Author Michael Lesy, perhaps best remembered for his discovery of the macabre sensibilities of Americans at the end of the 19th century in "Wisconsin Death Trip," brings that same relish for beneath-the-surface meaning to postcard images of American life between 1900 and 1910.

Naturally the very best photo in the collection (and the one used on the cover) is of San Franciscans frolicking in the surf below the old Cliff House, which seems to teeter on the edge of the cliff as well as impose its magnificence onto every fissure of rock.

Here, as at Boston's South Station, New York's Flatiron Building, San Francisco's Ferry Building, Cleveland's Lift Bridge, New Orleans' Crescent City Jockey Club and other municipal areas, the first thing we notice is how few people are walking around and how dignified and stately they seem to go about daily business and recreation.

It is not until Lesy reminds us that the population of the United States at the time (76 million) was less than a third what it is now that we realize this is "the world we have lost: its safety, its self- confidence, its vigor, its serenity, its possibilities -- its space."

This was not a perfect world, of course -- pictures of heaving smelters and "pickaninnies" are as alarming as forests cleared for settlement and orange groves edged out by developers. But it is a harbinger of our own time, as Lesy notes, when the population would explode, bringing so many more cars and phones and homes and the frenzied life along with it, and all the certainty of America's once-safe caste system lost to a few postcards. Lesy's work is a great book to ponder at the dawn of the 21st century.